1. Field of the Invention
The present invention relates to an image display device, and more particularly, to an image display device which facilitates to improve partial luminance in an image-display area by a local dimming method to partially control a backlight unit according to a display image, and simultaneously to reduce power consumption, and a driving method thereof.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device includes a liquid crystal display panel and a backlight unit, wherein the liquid crystal display panel is provided with plural liquid crystal cells arranged in a matrix-type configuration, and plural control switches for conversion of image data to be supplied to the plural liquid crystal cells. In this case, a transmittance of light emitted from the backlight unit is controlled in the liquid crystal display panel, whereby a desired image is displayed on a screen.
A related art backlight unit may be largely classified into a direct type and an edge type. In the direct type backlight unit, a light source is positioned at a rear side of a liquid crystal display panel, whereby the liquid crystal display panel is directly illuminated with light emitted from the light source. In the edge type backlight unit, a light source is positioned at one lateral side or both lateral sides of a liquid crystal display panel, whereby the liquid crystal display panel is illuminated with light emitted from the light source through the use of light-guiding plate. Especially, the direct type backlight unit can realize high luminance since the liquid crystal display panel is directly illuminated with light emitted from plural lamps, whereby the direct type backlight unit is chiefly used for a large-sized liquid crystal display device.
The related art backlight unit applies light with constant luminance to the liquid crystal display panel without regard to an image displayed on the liquid crystal display panel. Accordingly, since the constant luminance is maintained in the backlight unit without regard to the image displayed on the liquid crystal display panel, it is difficult to animatedly express an image with parts requiring high luminance, for example, explosion scene or flashlight scene. In addition, the continuous provision of the constant luminance causes the increase of power consumption.